ReverseGenerics.java

package com.suchowitzki.reversearray;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;
import java.util.ListIterator;

public class ReverseList {

    public static <T> List<T> reverse(List<T> list) {
        int size = list.size();

        ArrayList<T> obArray = new ArrayList<T>();
        obArray.addAll(list);

        ListIterator<T> iter = list.listIterator();
        for (int i = 0; i < size; i++) {
            iter.next();
            iter.set(obArray.get(size - 1 - i));
        }

        return list;
    }

    public static void main(String[] args) {
        LinkedList<Integer> linkedInt = new LinkedList<Integer>();
        ArrayList<Integer> arrayDouble = new ArrayList<Integer>();

        for (int k = 0; k < 10; k++) {
            int intNum = (int) (10*Math.random());
            int intNum2 = (int) (10*Math.random());
            linkedInt.add(intNum);
            arrayDouble.add(intNum2);
        }

        // LinkedList<Integer> demo
        System.out.println("Original LinkedList");
        System.out.println(Arrays.toString(linkedInt.toArray()));
        System.out.println("Reversed LinkedList with generic method.");
        System.out.println(Arrays.toString(reverse(linkedInt).toArray()));

        System.out.println("");

        // ArrayList<Double> demo
        System.out.println("Original ArrayList.");
        System.out.println(Arrays.toString(arrayDouble.toArray()));
        System.out.println("Reversed ArrayList with generic method.");
        System.out.println(Arrays.toString(reverse(arrayDouble).toArray()));

    }

}